The control can have Double-Byte Character Set (DBCS) characters in it. This flag is used with edit controls. It allows multiple-byte character sets.

DT_EDITABLE

The control can be edited; the value associated with the control can be changed. When this flag is not set, the control is read-only. This value is ignored on label, group box, standard push button, multivalued drop down list box and list box controls.

DT_MULTILINE

The edit control can contain multiple lines. This means a return character can be entered within the control. This flag is valid for edit controls only.

DT_PASSWORD_EDIT

Applies to edit controls. The edit control is treated like a password. The value is displayed using asterisks instead of echoing the actual characters entered.

Enables immediate setting of a value; as soon as a value in the control changes, MAPI calls the SetProps method for the property associated with that control. When this flag is not set, the values are set when the dialog box is dismissed.

DT_SET_SELECTION

When a selection is made within the list box, the index column of that list box is set as a property. Always used with DT_SET_IMMEDIATE.

This property is stored in the ulCtlFlags member of a control's DTCTL structure. Most of the control flags apply to all of the controls that allow user input; a few apply only to the edit control. Controls that do not allow user input, such as a button or a label, set 0 for their control flags.

Many of the flag values are self-explanatory. For example, when DT_REQUIRED is set for a control, it must contain a value before the dialog box is allowed to be dismissed. Either the service provider can supply a value through its IMAPIProp implementation or the user can enter one. DT_EDITABLE indicates that the value for the control can be modified. DT_MULTILINE allows the value for an edit control to span multiple lines.

Some control flags are not so obvious in their meaning. When a control sets the DT_SET_IMMEDIATE flag, any changes to its value take affect as soon as the user moves to a new control. MAPI makes a single call to the property interface's IMAPIProp::SetProps method for the control's property. This is different from the default behavior, which is to postpone having changes to control values take effect until after the user selects the OK button or dismisses the dialog box. The DT_SET_IMMEDIATE flag is often used in combination with display table notifications.

The following table lists the types of controls and all of the flag values that can be set for each type.